1. Field of the Invention
The present invention relates to an apparatus and method for retransmitting a message, and more particularly, to an apparatus and method for retransmitting a message that has failed to be transmitted by a source device in a message transmission system for transmitting a message from a source device to a destination device over a communication network.
2. Discussion of Related Art
In a message transmission system in which a plurality of terminals and a server are connected with each other over a wireless network, message transmission may be performed between a terminal and a server, and between terminals. The source device or the source indicates a terminal or server that generates and transmits a message upon an application's request, and the destination device or the destination indicates a terminal or server that receives the message and forwards it to the application.
In this case, even when the destination is unable to receive a message due to the state of the destination, the source may not be aware of the state and thus may have low message retransmission efficiency. This causes a problem that a message is repeatedly transmitted. In particular, this problem occurs when the destination is a terminal.
The conventional technology for retransmitting a message when the message fails to be transmitted is passive. For example, the message is retransmitted when a response is not received from a destination in a certain time period after a source has transmitted a message or when a retransmission request is received from the destination. In this case, if a plurality of messages are needed to be transmitted to the same destination, all the plurality of messages should be retransmitted. This causes a problem of increasing a system load.
Japanese Patent No. 4214793 discloses a method of determining retransmission timeout used in a wireless communication system. In detail, according to the method, the retransmission timeout is calculated by monitoring a packet round trip time, which is the difference between a time when transmission data is transmitted and a time when acknowledgement is received. However, a processing method when a plurality of pieces of transmission data are transmitted is not disclosed and thus it is difficult to improve retransmission efficiency.